/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.log4j.helpers;

import org.apache.log4j.spi.ErrorHandler;
import org.apache.log4j.spi.LoggingEvent;
import org.apache.log4j.Logger;
import org.apache.log4j.Appender;

/**
 * The <code>OnlyOnceErrorHandler</code> implements log4j's default error
 * handling policy which consists of emitting a message for the first error in
 * an appender and ignoring all following errors.
 * 
 * <p>
 * The error message is printed on <code>System.err</code>.
 * 
 * <p>
 * This policy aims at protecting an otherwise working application from being
 * flooded with error messages when logging fails.
 * 
 * @author Ceki G&uuml;lc&uuml;
 * @since 0.9.0
 */
public class OnlyOnceErrorHandler implements ErrorHandler {

	final String WARN_PREFIX = "log4j warning: ";
	final String ERROR_PREFIX = "log4j error: ";

	boolean firstTime = true;

	/**
	 * Does not do anything.
	 */
	public void setLogger(Logger logger) {
	}

	/**
	 * No options to activate.
	 */
	public void activateOptions() {
	}

	/**
	 * Prints the message and the stack trace of the exception on
	 * <code>System.err</code>.
	 */
	public void error(String message, Exception e, int errorCode) {
		error(message, e, errorCode, null);
	}

	/**
	 * Prints the message and the stack trace of the exception on
	 * <code>System.err</code>.
	 */
	public void error(String message, Exception e, int errorCode,
			LoggingEvent event) {
		if (firstTime) {
			LogLog.error(message, e);
			firstTime = false;
		}
	}

	/**
	 * Print a the error message passed as parameter on <code>System.err</code>.
	 */
	public void error(String message) {
		if (firstTime) {
			LogLog.error(message);
			firstTime = false;
		}
	}

	/**
	 * Does not do anything.
	 */
	public void setAppender(Appender appender) {
	}

	/**
	 * Does not do anything.
	 */
	public void setBackupAppender(Appender appender) {
	}
}
